Slashdot Mirror
Researchers Turn Tables and Walls Into "Scratch Input" Surfaces
An anonymous reader writes "Researchers at Carnegie Mellon University's HCI Institute have developed a new input technology that allows mobile devices to use surfaces they rest on, like tables, for gestural finger input. This is achieved with some clever acoustic tricks — basically taking advantage of high frequency sound propagation through dense materials. Their video highlights some neat applications, such as controlling an MP3 player by scratching on a wall and muting a cell phone by scratching on a table. Further details are available in the academic paper (PDF)."
The speed of sound in wood is approx 0.6-5 km/s making it not only highly anisotropic (due to the grain structure) but also giving it a long wavelength (20-160 cm @ 3 kHz).
Sorry; blame physics.
...has an institute devoted to hydrocloric acid? Talk about specialization gone mad.